Koob et al. have described methods of producing nordihydroguairetic acid (NDGA) polymerized collagen fibers of tensile strengths similar to that of natural tendon (e.g., about 91 MPa) to make medical constructs and implants. See, Koob and Hernandez, Material properties of polymerized NDGA-collagen composite fibers: development of biologically based tendon constructs, Biomaterials 2002 January; 23 (1): 203-12, and U.S. Pat. No. 6,565,960, the contents of which are hereby incorporated by reference as if recited in full herein.